Understanding Deflection of Cantilever: Direction of Moment M Explained

[chetzread]

Homework Statement

in the notes , i don't understand the circled part . I don't understand why the circled part moment M is in anticlockwise direction ... Shouldnt it be in clockwise direction ?

Homework Equations

The Attempt at a Solution

As we can see , the P at the one end will cause the cantilever to bend in clockwise direction . So , i think that the direction of moment M is wrong ...
It should point in clockwise dircetion , which means M = -P(∂ -y) , am i right ?

 

[PhanthomJay]

The sketch shows the internal force and moment at the cut section, required for equilibrium. Applied moment is clockwise, so internal moment is ccw. Applied force P is downward, so internal force P is upward.

 

[chetzread]

The sketch shows the internal force and moment at the cut section, required for equilibrium. Applied moment is clockwise, so internal moment is ccw. Applied force P is downward, so internal force P is upward.

ok, can you look at the example below, why the circled moment M is same direction with the moment due to applied force P?
since they are in the same direction,how can they are in equilibrium?

 

[chetzread]

The sketch shows the internal force and moment at the cut section, required for equilibrium. Applied moment is clockwise, so internal moment is ccw. Applied force P is downward, so internal force P is upward.

so, in the deflection equation, we are focusing on the internal moment? why?

 

[PhanthomJay]

The author assumed a clockwise internal moment but the calcs show in the 2nd images that it is actually negative or ccw. You again are looking at complex examples in trying to understand basic equilibrium concepts.